Method for preparing halogenated



Patented,fiiug. 3, 1937 STTE AENT

METHOD FOR PREPARING HALOGENATED INDANTHRONE No Drawing. ApplicationSeptember 10, 1934, Serial No. 743,419

9 Claims.

This invention relates to the preparation of halogen derivatives ofindanthrone (N-dihydro- 1,2,2',1'-anthraquinone azine) and moreparticularly to the selective dehalogenation of indanthrones containingmore than 2 atoms of halogen.

It is generally known that indanthrone itself which is not at all fastto chlorine may be rendered comparatively fast to bleach by theintroduction of halogen into the molecule. The higher halogenatedindanthrone compounds, containing more than 2 atoms of halogen permolecule, while being relatively fast to bleach, are quite easilyprecipitated from the solution in the vat, or as generally referred toin the trade, they lose the Vat readily, and are also very sensitive tocalcareous water thus rendering them unsuitable for dyeing in the vat oncommercial scale.

It has been found that the increase in the amount of halogen present inthe indanthrone molecule above approximately 2 atoms increases thesensitivity of these products in the vat until those compoundscontaining 4 or more atoms are so Lmstablein the vat that they cannotsatisfactorily be dyed in the ordinary manner.

Many attempts have been made to prepare a halogenated indanthrone whichwill be comparatively fast to bleach and still be sufficiently stable inthe vat to be satisfactory for use in large scale dyeing operations,wherein it is necessary to hold the vat for periods of an hour or more.

A number of methods for halogenating indanthrone have been described inthe literature and apparently the method by which the halogen isintroduced in the indanthrone molecule is an important factor in theultimate properties of the dyestuff. By some methods more chlorine mustbe introduced in the indanthrone molecule to obtain the same degree offastness to chlorine that is obtained by the introduction of lesschlorine by other methods. In the halogenation of indanthrone by theknown methods a point is reached beyond which further halogenation doesnot increase the bleach fastness. In some cases this is. as low as 15%chlorine, while in others it is as high as 20%. It has also been foundthat in continuous dyeing operations on commercial scale with higherhalogenated indanthrones, where the vat is held for any extended periodof time, the bleach fastness of the goods dyed at the end of the periodis noticeably impaired in comparison with the bleach fastness of thegoods dyed at the beginning of 5 the operation. It is also known that inthe Vatting of these products, the halogen content of the molecule isdecreased during the vatting procedure, and it is believed that thehalogen that is liberated in the vatting procedure combines with thealkali present to form. a salt which precipitates the dyestufi. Since inthe vatting of the higher halogenated indanthrones the amount of halogengiven on is greater than in the vatting of the lower halogenatedproducts, more of the dyestuff is liable to be precipitated, which wouldapp-ear at least in part to account for the decreased stability of theirvats.

It has been found that dichloro-indanthrone containing the chlorine inthe 3 positions is as fast to bleach as any of the higher chlorinatedproducts prepared by known methods, and that it is also more stable inthe vat than the higher halogenated products and less sensitive tocalcareous water. I have also found that when this product is vatted bythe normal procedure, less chlorine is liberated under the sameconditions than is liberated from some dichloroindanthrone bodies whichhave been prepared by direct chlorination, and which because they arealso deficient in bleach fastness are believed to contain part of thechlorine in other positions.

It is therefore concluded that only the halogen in the 3 positions inthe indanthrone molecule exerts a favorable influence on the bleachfastness of the product and that this halogen is more firmly attachedthan the halogen that may be present in other positions. Because of thegreater stability of this halogen, it is not so readily attacked in thevatting procedure, although it is to be understood of course that eventhis halogen may be split oiT by vatting at the usual vattingtemperatures if the vat is held for any extended period. This inventiontakes ad-; vantage of my finding that the halogen present in thosepositions which have the least influence on good bleach fastness can beselectively re moved by controlling certain conditions in the vattingprocedure, and that when this de halogenation is allowed to proceed to asubstantially dihalogen body, maximum bleach fastness, stability andsolubility are reached.

It is therefore an object of this invention to provide a process wherebyhigher halogenated indanthrone compounds are partially dehalogenatedunder such conditions that only that part of the halogen is removed fromthe indanthrone molecule which adds little or nothing to the bleachfastness of the dyeings and prints obtained from color pastes andpowders produced therefrom, whereas that part of the halogen whichexerts a favorable influence upon the fastness properties is invariablyretained.

It is a further object of my invention to produce dihalogen indanthronecompounds from less desirable higher chlorinated and brominatedindanthrones which are equal in fastness properties to the originalhigher chlorinated and brominated compounds but which are greatlyimproved in their stability in the vat and are less sensitive tocalcarous water.

It is a still further ob'ect of my invention to provide a processwherein the dehalogenation may be carried out in ordinary tap water (ascompared to distilled water).

It is a further object of this invention to provide a process fordehalogenating the higher halogenated indanthrone bodies which may becarried out at ordinary room temperatures.

It is a still further object of my invention to provide a method forvatting halogenated indanthrones containing 2 or more atoms of halogenper molecule at ordinary temperature by the use of vatting assistants.

In general my invention consists in the selective dehalogenation ofknown halogen-indanthrones containing more than 2 atoms of halogen permolecule which may be prepared by halogenating indanthrone by any of theknown methods, such as in nitrobenzene, sulfuric acid, sulfurylchloride, fused sulfur, acetic acid, etc., and those compounds preparedby the partial or complete replacement of bromine by chlorine, asdisclosed in U. S. Patents 1,862,843, 1,862,844 and 1,862,865, byvatting in distilled or ordinary tap water at temperatures between 5 and35 C. and in the presence of vatting assistants when necessary tomaintain them in solution in the vat. The products prepared according tomy invention are fully equal in bleach fastness to the parent bodies andare improved thereover in regard to solubility and stability in the vatand sensitiveness toward calcareous water in the vatted state, sinceonly that part of the halogen is removed from the indanthrone moleculewhich adds little or nothing to the bleach fastness of the resultinghalogen-indanthrone, whereas'that part of the halogen which exerts afavorable influence upon the bleach fastness properties of the dyestuifis invariably retained.

According to my invention, halogenated indanthrone compounds are vattedat temperatures not materially above 35 C. and preferably between 15 and35 C. for A to 2 hours, either in distilled water or in hard water witha vatting assistant, by employing .5 to 1.0 part of sodium hydrosulfiteand .5 to 1.0 part of caustic soda per part of indanthrone body. Thevatting assistant may be omitted provided the vat used is very dilute,or provided distilled or very soft water is used, or when the causticsoda is replaced by an equivalent amount of potassium hydroxide,although I prefer to employ small amounts of certain vatting assistant$0 that the process may be carried out in more concentrated vats usingordinary hard water and the less expensive caustic soda.

In general, I may use any of the vatting assistants which have beendescribed in the prior art for indanthrone colors, such as thecondensation products of ethylene oxide and ammonia (U. 5. Patent1,923,178), the polymerized ethylene oxide and condensation products ofethylene oxide described in French Patent 727,202, and preferably thoseWater-soluble condensation products of dichlorhydrin and epichlorhydrinwith ammonia and water-soluble primary amines, which are described in U.S. Patents 1,977,251, 1,977,253 and 1,977,272. Other aliphatic amines ofhigh molecular weight, such as polymerized ethylene diamine, have alsobeen found to serve equally well as stabilizers for the higherhalongenated indanthrone vats at ternperatures below 35 C.

While the dehalogenation reaction usually is completed to the desireddegree after the vats have been kept at 3032 C. for about one-half hour,I prefer to prolong the time of vatting to at least 1 to 2 hours inorder to be certain that that part of the halogen is removed completelyfrom the indanthrone molecule, which does not influence the bleachfastness of the dyeings and prints, since I have found that my noveldehalogenating procedure does not impair the bleach fastness of thecolor, even when the vatting is continued for as long as 15 hours,provided that the temperature is not permitted to rise appreciably above35 C. With conditions otherwise the same, if the vatting is carried outat 40 to 50 C. (the usual vatting temperatures), the resulting dyestuffsare noticeably inferior in bleach fastness and as a rule dye lessdesirable greenish-blue and dull shades.

The following examples are given to more fully illustrate my invention.The parts used are by weight.

Example 1 25 parts of an acid pasted chlorinated indanthrone compoundprepared according to German Patent 331,283, and containing 17.57%chlorine is suspended in 2000 parts of ordinary water (-400 partshardness per million). There are then added 2 parts of the hydrochloricacid addition salt of the epichlorhydrin-ammonia condensation productdescribed in U. S. Patent 1,977,251, and the temperature is adjusted to30 to 32 C. 20 parts. of sodium hydroxide and 25 parts of sodiumhydrosulfite are now added and the vat is stirred at 30 to 35 C. for 2hours. The indanthrone body may be isolated from this vat in anysuitable manner, forinstance, by air blowing the vat for several hoursand recovering the oxidized dyestuff by filtration, or the vat may besalted until the leuco compound is precipitated out of solution and theprecipitate filtered off and, if desired, oxidized by treatment withoxidizing agents or simply by exposing the filtered off leuco filtercake to the air. In any case, the product obtained is substantially adichloro-indanthrone containing 13.5 to 14% chlorine. It dyes and printscotton in reddish-blue bright shades of equal bleach fastness incomparison with the parent body (trichloro-indanthrone), and is quitelnsensitive to calcareous water.

When the same halogenated indanthrone body as used above is vatted inthe ordinary manner with alkaline hydrosulfite and in distilled water attemperatures of 50-55 C. and in the absence of a vatting assistant. for12 hours and the product isolated in the same manner, :a chlor'matedindanthrone of 12.4% chlorine content is obtained which dyes cotton inshades which are somewhat more greenish and duller and which aredistinctly less fast to bleach than dyeings obtained from the parenttriohloro-indanthrone.

Example 2 A dyestuif paste containing 100 parts of atrichloro-indanthrone prepared by chlorinating indanthrone innitrobenzene suspension with chlorine gas until the chlorine content was18.2%, is suspended in 9500 parts of ordinary water (75-100 partshardness per million), containing 10 parts of the condensation productof epichlorhydrin and ethylene diamine, described in U. S. Patent1,977,253. There are then added parts of caustic soda. The temperatureis adjusted to 32 C. and 100 parts of sodium hydrosulfite are stirred inthe suspension. The vat is stirred for 2 hours at 32 to 34 C. and theproduct isolated in either of the ways disclosed in Example 1. Theproduct thus obtained is a dichloro-indanthrone containing 13.1%chlorine. It dyes cotton bright blue shades of equal bleach fastness incomparison with dyeings obtained from the originaltrichloro-indanthrone, and is insensitive to calcareous water containing75 parts hardness per million.

Example 3 A color paste containing 100 parts of the bromine containingchlorinated indanthrone body described in U. S. Patent 1,862,843,Example 4 (containing 14.5-15.5% chlorine and 1.'5-3.'0% bromine), issuspended in 9000 parts of ordinary hard water, containing 15 parts ofthe condensation product of epichlorhydrin and monomethylamine,described in US. Patent 1,977,253.

There are then added at 30 C. 75 parts of caustic soda and parts ofsodium hydrosulfite and thevat is stirred at 28 to 32 C. "for 1 hoursand then salted with parts of common salt. The mass is air blown for 2to 3 hours or until the oxidation to a bright blue precipitate iscomplete. The product is filtered off, the cake is washed alkali freewith cold water. The dyestuff thus obtained contains 11.5 to 12.5%chlorine and 0.5 to 1.5% bromine on the solids basis. It dyes and printscotton in reddish-blue shades, which are equally as bright and fullyequal in fastness towards chlorine in comparison with the parent body.The vatted product, which contains less chlorine and bromine, ispractically insensitive towards calcareous water, whereas the unvattedstarting material, containing more chlorine and bromine, cannot bevatted successfully in water of about 100 parts hardness per million.

In place of the 15 parts of the condensation product of epichlorhydrinand monomethylamine, 20 parts of the assistant described in Example 2 ofFrench Patent 727,202 (diethyleneglycol heated with ethylene oxide andthe reaction product condensed with oleic acid), or 20 parts of thecondensation product of ethylene oxide with ammonia, described in U. S.Patent 1,923,- 178, may be used to maintain the halogenated indanthronebody in solution during the vatting procedure. Similar results areobtained to those described above.

When distilled water is employed for the vatting procedure (at 28 to 32C.) or when postassium hydroxide is used in equimolar amounts instead ofcaustic soda in distilled'or hard water, the vatting assistant may beomitted and the same end product is obtained as long as the Example 4100. parts of the bromine containing chlorinated indanthrone body usedin the'preceding example are suspended in 9000 parts of ordinary tapWater (containing '7 5-100 parts hardness per million). There are thenadded at 30 C. 112 parts of potassium hydroxide and 100 parts of. sodiumhydrosulfite. The vat is stirred for 1 hours during which time noprecipitation takes place. There are then added 100 parts of sodiumchloride. The precipitate is filtered 01-1, and the filter cake issuspended in 300 parts of water and air blown for 3 hours. The resultingdyestufi dyes cotton in bright blue shades of equal bleach fastness incomparison with the starting material and is substantially insensitiveto calcareous water in the vat, whereas the original bromine containingchlorinated indanthrone body is very sensitive to calcareous water and.cannotjbe satisfactorily dyed in hard water by the usual dyeing methods.

Example 5 100 parts of monobromo-monochloro-indanthrone as obtained bythe procedure described in U. S. Patent 1,862,865 (containing about 15%bromine and 6.5% chlorine) is vatted with the addition of 10 parts ofthe condensation product of epichlorhydrin and ethylene diamine(described in U. S. Patent 1,977,253) 80 parts of sodium hydroxide and100 parts of sodium hydrosulfite in 10,000 parts of ordinary tap water,while keeping the temperature below 35 C. After stirring the vat for twohours at 32 to 35 C., the dyestufi? is isolated by either of the methodsdescribed in Example 1. The product thus obtained is less sensitivetowards hard water vats,

but equal in bleach iastness and brilliancy of shade in comparison withthe starting material. It is lower in chlorine and slightly lower inbromine content than the unvatted starting material.

Example 6 30 parts of'athe tetrachloro-indanthrone obtained bychlorination of indanthrone in nitrobenzene according to the processdisclosed in Example 2 of U. S. Patent 1,847,329 and which contains23.21% chlorine, was acid pasted by dissolvingin 200 parts of sulfuricacid and drowning-in 2000 partsof cold water. The precipitate isfiltered off, washed acid free and milled to a smooth paste. An amountof this paste equal to 15 parts of tetrachloro-indanthrone (100%) issuspended in 1200 parts of ordinary tap water of about 100 partshardness per million, containing 1.5 parts of the condensation productof epichlorhydrin and ammonia, described in U. S. Patent 1,977,251.There are then added 15 parts of caustic soda and the temperature isadjusted to 30 to 32 C. 20 parts of sodium hydrosulfite are now addedand the vat is stirred at a slow rate for two hours. It will be observedthat the color of the vats may be varied within wide limits.

body remains in perfect solution during the entire course of the twohours stirring.

The reaction product may be isolated from this vat by the procedureoutlined in Example 1. The resulting product is substantially adichloro-indanthrone of 13.5-14.0% chlorine content, which dyes andprints in bright reddish-blue shades of fully equal fastness propertiestowards chlorine in comparison with the parent color paste consisting oftetrachloro-indanthrone.

When a similar amount of the tetrachloro-indanthrone above used issuspended in 1500 parts of distilled water at 50 C. and vatted withparts of caustic soda and parts of sodium hydrosulfite at temperaturesof 50 to 55 C., it is found that after hour of vatting, precipitation ofa greater amount of the dyestuff takes place, which cannot be broughtback into solution by adding more caustic and hydrosulfite or by raisingthe temperature. After stirring the vat for 2 hours at this temperature,the product is isolated by the method indicated in Example 1. It is achlorinated indanthrone of 12.4% chlorine content, which dyes cotton insomewhat more greenish and duller blue shades which are distinctly lessfast to bleach in comparison with the dyeing obtained from the parentunvatted color paste.

It will be understood that the amounts of alkali and hydrosulfite aswell as the degree of dilution As long as the color can be vatted underthe conditions employed, a selective dehalogenation, which leaves thatpart of the halogen intact which is instrumental in imparting bleachfastness to the indanthrone molecule, can be effected according to thisinvention by maintaining the vatting temperature below 35 C. Experimentshave shown that the vatting procedure according to this invention may becarried out successfully at temperatures as low as plus 5 C., providedthat a vatting assistant is employed which is capable of holding thecolor in the vatted state in solution for about A; to 1 /2 hours at thislow temperature.

It is not necessary to maintain mechanical agitation throughout theentire process, nor to maintain the temperature within narrow limits,when a complete vat has been obtained, except that the temperatureshould not be allowed to rise above about 35 C.

In all cases where it is desired to obtain halogenated indanthronebodies having maximum fastness to bleach, the halogenated indanthrone tobe treated must contain suflicient halogen so that the introduction ofadditional amounts of halogen does not increase its bleach fastness.

I claim:

1. The process for preparing dichloro-indanthrones from higherchlorinated bodies which comprises reacting such higher chlorinatedindanthrone bodies in an alkaline hydrosulfite solution at temperaturesnot materially above 35 C., in the presence of a vatting assistant,until no further chlorine is removed.

2. The process for preparing dichloro-indanthrones from higherchlorinated bodies which comprises reacting such higher chlorinatedindanthrone bodies in an alkaline hydrosulfite solution at temperaturesnot materially above 35 C., in the presence of a vatting assistant ofthe group consisting of water-soluble condensation products of ammoniaor a water-soluble primary aliphatic amine with dichlorhydrin orepichlorhydrin, until no further chlorine is removed.

3. The process for preparing dihalogen-indanthrones from higherhalogenated bodies which comprises reacting such higher halogenatedindanthrone bodies in an alkaline hydrosulfite solution at temperaturesnot materially above 35 C., in the presence of a vatting assistant,until no further halogen is removed.

4. The process for preparing dichloro-indanthrones from higherchlorinated bodies which comprises reacting such higher chlorinatedindanthrone bodies in an alkaline hydrosulfite solution at'temperaturesnot materially above 35 C. until no further chlorine is removed.

5. In the process for eliminating that halogen from the molecule of ahalogen containing indanthrone compound which adds nothing to the bleach'fastness of such compound by subjecting it to the action of an alkalinehydrosulfite solution, the step which comprises maintaining the solutionat a temperature not materially above 35 C. until no further halogen isremoved at that temperature.

6. In the process for eliminating that halogen from the molecule of ahalogen containing indanthrone compound which adds nothing to the bleachfastness of the compound, the step which comprises subjecting thehalogenated indanthrone to the action of an alkaline hydrosulfitesolution maintained at a temperature not materially above 35 C., in thepresence of a vatting assistant, and continuing the reaction until nofurther halogen is removed at that temperature.

7; The process which comprises vatting a chlorinated indanthronecompound containing more than two atoms of chlorine in an alkalinealkali metal hydrosulfite solution at a temperature not materially above35 C.'in the presence of a vatting assistant.

8. The process which comprises vatting a halogenated indanthronecompound containing more than two atoms of halogen in an alkaline alkalimetal hydrosulfite solution at a temperature not materially above 35 C.in the presence of a vatting assistant.

9. The process which comprises vatting a halogenated indanthronecompound which contains no substituents on the azine nitrogen atoms inan alkaline alkali metal hydrosulfite solution at a temperature notmaterially above 35 C.

O'I'I'O STALLMANN.

